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VanWoert ND Rowe DB Andresen JA Rugh CL Fernandez RT Xiao L 《Journal of environmental quality》2005,34(3):1036-1044
Urban areas generate considerably more stormwater runoff than natural areas of the same size due to a greater percentage of impervious surfaces that impede water infiltration. Roof surfaces account for a large portion of this impervious cover. Establishing vegetation on rooftops, known as green roofs, is one method of recovering lost green space that can aid in mitigating stormwater runoff. Two studies were performed using several roof platforms to quantify the effects of various treatments on stormwater retention. The first study used three different roof surface treatments to quantify differences in stormwater retention of a standard commercial roof with gravel ballast, an extensive green roof system without vegetation, and a typical extensive green roof with vegetation. Overall, mean percent rainfall retention ranged from 48.7% (gravel) to 82.8% (vegetated). The second study tested the influence of roof slope (2 and 6.5%) and green roof media depth (2.5, 4.0, and 6.0 cm) on stormwater retention. For all combined rain events, platforms at 2% slope with a 4-cm media depth had the greatest mean retention, 87%, although the difference from the other treatments was minimal. The combination of reduced slope and deeper media clearly reduced the total quantity of runoff. For both studies, vegetated green roof systems not only reduced the amount of stormwater runoff, they also extended its duration over a period of time beyond the actual rain event. 相似文献
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木材热解是木材类火灾事件的先导过程,是引起后续的阴燃、着火、燃烧和火焰蔓延等各种现象的重要因素,因此研究木材的热解非常重要。采用热重分析法对番龙眼木的热重特性及反应动力学进行研究。在空气气氛下,研究样品粒径、试验气氛和升温速率对番龙眼木热解特性的影响。对番龙眼木的热解反应过程的分析,采用Flynn-Wall-Ozawa积分法、Kissinger最大速率法和atava-esták积分法对动力学进行处理。试验得到了一些热解动力学的参数,并推断出不同温升速率下番龙眼木的动力学最概然机理方程为反应级数函数,n=4 相似文献
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广东一饮用水源地河流沉积物及鱼体中氟喹诺酮类(FQs)抗生素残留特征研究 总被引:2,自引:0,他引:2
本研究对广东一饮用水源保护区的河流氟喹诺酮类(Fluoroquinolones,FQs)抗生素进行分析.采用高效液相色谱法定性定量分析9个沉积物样品和5种鱼肉及1种鱼内脏中3种FQs—诺氟沙星(Norfloxacin,NOR)、环丙沙星(Ciprofloxacin,CIP)、恩诺沙星(Enrofloxacin,ENR)的残留特征,并与沉积物中有机质、总氮、总磷进行Person相关性分析.结果表明:河流沉积物各点平均值NORCIPENR,最大含量分别为:NOR248.25 ng·g-1,CIP 158.69 ng·g-1,ENR 56.81 ng·g-1;FQs和沉积物有机质、总磷相关系数平均为0.946、0.968(p0.01);5种鱼的鱼肉中FQs的含量可能高于或低于沉积物中FQs含量均值;鳙鱼内脏FQs含量是鱼肉中的3.21~9.53倍.研究结果对保障饮用水安全及水产品生态安全具有重要的意义. 相似文献
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Microwave (MW) hybrid processes are able to disrupt the flocculent structure of complex waste activated sludge, and help promote the recovery of phosphorus as struvite. In this study, to optimize struvite yield, (1) the characteristics of matter released in MW-hybrid treatments were compared, including MW, MW-acid, MW-alkali, MW-H2O2, and MW-H2O2-alkali. The results showed that selective release of carbon, nitrogen, phosphorus, Ca2 +, and Mg2 + achieved by sludge pretreatment using MW-hybrid processes. MW-H2O2 is the recommended sludge pretreatment process for phosphorus recovery in the form of struvite. The ratio of Mg2 +:NH4+-N:PO43 −-P was 1.2:2.9:1 in the supernatant. (2) To clarify the effects of organic matter on struvite recovery, the composition and molecular weight distribution of organic matters were analyzed. Low molecular weight COD was found to facilitate the removal rate of NH4+-N and PO43-P via crystallization, and the amorphous struvite crystals (< 1 kDa) from the filtered solutions had high purity. Therefore, the present study reveals the necessity of taking into consideration the interference effect of high molecular weight organic matters during struvite crystallization from sewage sludge. 相似文献